1. Field of the Invention
This invention relates to exterior lights of the type used to illuminate streets and walkways. More particularly, the invention relates to exterior lights, including decorative exterior lights, that are adjustable to produce a desired illumination distribution.
2. Description of Related Art
There are many different types, styles and designs of exterior lights available on the market. However, most of these designs are not suitable for illuminating streets where the distribution of emitted light must meet rigorous standards as to glare, cutoff angle, throw and direction of emitted light, as well as the shape and size of the lighted area. Recognized industry groups such as the Illuminating Engineering Society (IES) set predetermined illumination distribution standards, such as the Type II, Type III and Type IV distribution patterns, among many others. Lighting engineers designing street lighting use these recognized standards to specify the desired lighting.
An exterior light capable of meeting one of the recognized illumination distribution standards (e.g. Type II) must be highly engineered. As a result; such a light is normally not adjustable to any other standard. The lighting engineer will purchase a Type II light to meet a requirement for a Type II lighting distribution, and a Type III light to meet a Type III lighting requirement, etc.
In addition to controlling the illumination pattern on the ground horizontally surrounding the light, it is important to control the vertical distribution of emitted light. Two predefined vertical light emission limits are referred to as xe2x80x9ccutoffxe2x80x9d and xe2x80x9csemicutoff.xe2x80x9d Exterior lights providing adjustment of the vertical characteristics of the emitted light to cutoff and semicutoff as well as adjustment of the horizontal characteristics of the emitted light have not been available.
Furthermore, engineered exterior lights capable of meeting one of the predefined illumination distribution standards are commonly designed for government regulated street lighting applications and are typically available only in a generic modern style which many architects considered unattractive. Engineered exterior lights capable of being adjusted to meet multiple different IES lighting standards have not been available in decorative, antique or reproduction styles.
Even in applications that do not actually require the exterior light to meet a predefined illumination distribution standard, control over the lighting distribution is necessary to limit objectionable light pollution and glare. Exterior lights are available with various movable reflectors, shields and bulb holders to provide adjustment of the lighting pattern and control light trespass. However, adjustment of these designs is very difficult because changing the position of the bulb to change the lighting distribution has also changed the relationship between the bulb and the shield that controls light trespass. If it is desired to change the size or shape of the lighting pattern, which requires adjustment of the bulb position, the location of the shield must also be changed.
Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide an exterior light having a shield that can be adjusted relative to the bulb to control the horizontal distribution of light and light trespass and wherein the bulb and shield are mounted together and can be adjusted together to change the vertical light distribution without significantly altering the shape of the horizontal distribution and the relationship between the bulb and the shield.
It is another object of the present invention to provide an exterior light that has a decorative appearance, such as a reproduction street light gasolier, that produces a predetermined illumination distribution that matches an illumination standard set by a recognized industry group, such as the Illuminating Engineering Society.
It is yet another object of the present invention to provide an exterior light that can be adjusted to produce different selected predetermined illumination distributions from among multiple recognized illumination distribution standards set by a recognized industry group, such as the Illuminating Engineering Society.
It is a further object of the present invention to provide an exterior light that has an upper translucent portion providing controlled upwardly directed lighting.
Another object of the present invention is to provide an attractive exterior light that eliminates disability glare, has a low discomfort glare rating and a high visual comfort probability and is adjustable in cutoff, throw and illumination pattern to make it suitable for multiple different roadway lighting applications.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
The above and other objects, which will be apparent to those skilled in art, are achieved in the present invention, which is directed to an exterior light including a base, a transparent enclosure mounted on the base, a bulb mounted within the enclosure on a vertically adjustable bulb holder, a shield mounted on the bulb holder for adjustable movement relative to the bulb and an upper dome cooperating with the bulb to produce an illumination distribution. As the bulb holder is vertically adjusted, the shield and bulb move together. Adjustment of the bulb holder and the shield changes the illumination distribution.
In one aspect of the invention, the upper dome has a primary reflector mounted inside it having a shape that cooperates with the bulb, the shield and the lower edge of the dome to produce a predefined illumination distribution according to an illumination distribution standard set by a recognized illumination standard setting society, such as the Illuminating Engineering Society. In the preferred design, the light can be adjusted to multiple different predetermined illumination standards, including Type II, Type III and Type IV roadway illuminations.
In another aspect of the invention the primary reflector includes at least one opening for transmitting light and the upper dome is translucent. This produces an upward illumination and an attractive appearance simulating early gasolier street light designs. In a different aspect of the invention the upper dome is internally metallized.
The shield may act as a secondary reflector and is preferably substantially vertical. The primary reflector preferably has at least two substantially planar reflective surfaces, and most preferably has at least four substantially planar reflective surfaces, two surfaces being inwardly facing and two being outwardly facing.
In the most highly preferred embodiment of the invention, the exterior light has a decorative appearance simulating a non-electric luminaire, such as an antique gasoliere design having at least one simulated gas mantle illuminated by the bulb.